ISS006-E-33079 (24 February 2003) --- Astronauts Kenneth D. Bowersox (right) and Donald R. Pettit, Expedition Six mission commander and NASA ISS science officer, respectively, participate in a scheduled extravehicular activity (EVA) development test objective (DTO) in the Quest Airlock on the International Space Station (ISS). The test demonstrated the ability of two crewmembers to safely get into the American Extravehicular Mobility Unit (EMU) spacesuit without the assistance of a third crewmember; that ability is a prerequisite to sending smaller crews to ISS while the space shuttle fleet remains grounded during the investigation of the Columbia accident. Bowersox and Pettit helped each other into their EMU spacesuits, donned jet backpacks called Simplified Aid for EVA Rescue (SAFER), set up the necessary equipment for a pre-breathe of oxygen to purge nitrogen from their bloodstreams, and then got out of the spacesuits.